Low-voltage spark plug



, Nov. 29, 1966 w. BEYE SMITS LOW-VOLTAGE SPARK PLUG Filed June 4, 1958 INVENTOR.

WY'IZE BEYE SMITS Unite LOW-VOLTAGE SPARK PLUG Wytze Beye Smits, 27 Prinses Mariannelaan, Voorburg, Netherlands This invention relates to spark plugs and more particularly to a low-voltage surface discharge spark plug in which there are no electrodes as such.

Low voltage surface discharge spark plugs are well known in the art. Such plugs generally comprise a pair of concentrically disposed electrode with an intermediate layer of a semi-conductive material. Upon the application of a comparatively low voltage the spark will creep from one electrode to the other across the semi-conductive layer. This produces a satisfactory spark for ignition purposes and the plug will operate efiiciently irrespective of the amount of oil or soot on the face of the plug. However, the semi-conductive layer between the electrodes tends to wear away and thus the useful life of the plug is decreased.

The present invention provides a spark plug which operates on low-voltage but which has no intermediate semiconductive layer and consequently there are no parts which tend to wear away. According to the present invention the spark plug comprises a closely wound coil of wire or the like which is connected between the terminals on the plug. The wire need not be formed in a spiral coil but may be curved in any desired manner. The plug is operated on a condenser discharge and the passage of current through the coil produces a highly ionized field between the coils and consequently only a small portion of the condenser energy flows through the coil. The major portion of the energy discharges from one winding to the next in the form of sparks. The coil provides a large surface for cooling purposes and as there are no electrodes or intermediate insulating layer, there are no parts which are subjected to great wear. The conductor forming the coil is provided with insulation which may be in the form of an oxide skin or by coating with enamel, varnish or glass. Alternatively the insulator between the conductor windings may consist of a loose strip of insulation material such as, for example, mica, which is deposed between the coils of bare wire.

An objective of the present invention is to provide a spark plug which operates on low-voltage and which has no electrodes.

A further object of the present invention is to provide a spark plug in which the terminals on the plug are interconnected by a closely wound coil and in which the spark jumps from one coil to the next in a highly ionized field.

Other objects and many of the attendant advantages of the present invention will become apparent upon consideration of the following detailed specification in connection with the accompanying drawing wherein:

Fig. 1 shows one embodiment of the presently disclosed spark plug, and

Fig. 2 shows a modification thereof.

Referring now more specifically to Fig. 1 there is shown at 1 the body of the spark plug which is provided with screw threads 2 and an insulator portion 3 which may be made of porcelain or the like. Adjacent one end of the plug there is one terminal 4 which is connected through the plug with the terminal 8. At 5 there is shown a wire which is onnected at one end 7 thereof to the terminal 8 and is closely wound in a coil and has the outer end 6 connected to the plug body forming the other ter- States Patent 0 minal. The wire need not be formed as a spiral coil but may be curved in any desired manner.

The wire 5 may be provided with an insulating coating formed by oxidation or, alternatively, the wire may be coated with enamel or glass. The layer of the plug beneath the winding may be formed of insulating material and the wire coil may be wound on this insulating sublayer and fixed in place by enamelling or the like.

it is also possible to provide an insulating sub-layer in which the coil is formed by a groove and the conductive material applied to this groove by evaporating, spraying or sintering.

In Fig. 2 there is shown a modification in which the plug body I has screw threads 2 formed thereon with an end portion 9 of reduced diameter, the end portion being made of insulating material such as porcelain or the like. The central electrode extends through the end portion 9 and the end 8 of this electrode projects from the body. The coil 10 is wound around the outer surface of the end portion 9 and the inner end 11 of the coil 11} is connected to the plug body and the outer end 12 thereof is brought over the end surface of the end portion 39 and connected to the projecting terminal 8. The wire is insulated by oxidation or other suitable means as described hereinbefore.

Upon the application of a low-voltage to the terminals of the plug by way of a condenser discharge a small amount of current will flow through the coil and this current flow will produce a highly ionized field and the major portion of the condenser will discharge by way of sparks jumping across the windings of the coil. In this way sparks are produced without the provision of any electrodes and without any semi-conductive layer between electrodes which tends to become worn away after repeated use.

Obviously many modifications and variations of the present invention are possible in light of the above teachings. What is claimed as new and desired to be secured by Letters Patent is:

l. A spark plug comprising a plug body, an insulative layer on said plug body, a conductor wound in the form of a coil on said insulative layer, and terminal means to connect said conductor to a source of electrical energy.

2. A spark plug adapted to operate on a low-voltage discharge comprising a plug body, a pair of terminals, a conductor interconnecting said terminals, said conductor being disposed on said plug body in the form of a closely wound coil.

3. A spark plug according to claim 2 wherein said conductor is wound on a fiat surface of the plug body.

4. A spark plug according to claim 2 wherein said conductor is wound on a cylindrical projection on the plug body.

5. A spark plug according to claim 2 wherein said conductor is insulated by an oxide coating.

6. A spark plug according to claim 2 wherein said conductor is insulated by a varnish coating.

7. A spark plug according to claim 2 wherein the conductor is insulated by enamelling.

8. A spark plug according to claim 2 wherein the conductor is insulated by coiling together with an insulative tape.

9. A spark plug according to claim 2 wherein the conductor is sprayed metal.

10. A spark plug according to claim 2 wherein the conductor is precipitated metal.

11. A spark plug according to claim 2 wherein the conductor is sintered metal.

References Cited in the file of this patent UNITED STATES PATENTS 1,589,489 Snook June 22, 1926 

